Corner Assembly Clamp Blocks

These are more of a set of assembly jigs than a WW project, but I think these are going to help me greatly. I am fairly confident in preparing frames and casework, but seem to come up short in ASSEMBLY.

As I’m planning some upcoming cabinet projects I went looking for commercial corner clamps to help with that. Whoa…they can be pricey epsecially when you might need a dozen or more of them! I took a look in the scrap bin for some 3/4 Birch ply and came up with these pictured. I doubled the ply for a wider clamping surface. There are 3 sizes. Notice the 45 degree center spot to clamp at the center if needed (as such they will need to be used on the inside of corners instead of the outside).

I was carefully when these were cut out on the TS to get the 90 very close. Finished each 90 on the wide belt sander and 12” disk sander checking frequently till the machinists square showed no light and were spot on the 90. Note the square in the second pic.

Finished with several coats of shellac and spray acrylic to keep any glue from sticking on assembly.

These are excellent – the ones from Rockler are pretty expensive and the surfaces aren’t quite flat – they’re a little wavy, but probably fine for woodworking. They are very rigid, though.

One nice thing about the Rockler clamping squares is that they can be used on the outside of a corner. Have you considered making squares that can be used that way? You’d have to cut away the angle brace area on your current design and drill a little hole at the corner for relief. That might affect the rigidity, although they look pretty beefy to begin with.

Thank you all for your comments. When I can easily make a jig or tool instead of buying them it allows purchases of the things I can’t make…like saw blades,etc.

WCH, agreed these corner blocks can only be used to clamp on the inside of a corner. I don’t see the downside there though. Time will tell if I need to pull some more 3/4 plywood scrap from the cutoff bin to make some outside corner clamps.

yup. grrrrreat idea. there are far too many “gizmos” on the market such as this that cost way way too much money…. I’m sure it doesn’t cost these companies (not mentioning any names, but they know who they are) THAT much to make things such as this…... Very great idea, and simple….Thanks for sharing

It’s been some time since this has been up; this just came through on rotation and thought it deserved renewed currency.

Ratchet’s excellent post is a wonderful time- and money-saving project for LJs everywhere.

By doubling up on the ply gives a greater clamping area and makes for an easier to handle block when fumbling with getting those “just right” corner alignments. To my knowledge, this one gives a wider surface area than any commercial clamp block currently available. I like it.

It ain’t as easy as one would think making a precise corner block. I’ve tinkered with various assembly blocks, coming away with a mixed bag. An accurately cut square of 3/4 MDF with holes to accept clamp heads remains a good user. Right now on the work table: a 4” steel L bracket carefully screwed to pcs. of milled flat oak with a thin layer of cork for a cushiony friction grip holds promise.

In all the years roaming through the hardware cafeterias of HD and Lowe’s, I’ve never seen one. And, you would think HF would jump their discount feet into offering something like this, but, no!

Perhaps it’s time for a clever consortium of LJs to offer a select catalog of quality wood jigs, fixtures and work aids priced right. (??)